1. Field of the Invention
The present invention relates to an auto disc changer which can store a large number of audio discs and play back the discs one at a time.
The present invention relates to a disc confirmation apparatus for disc stocker which is suitable for an auto disc changer.
2. Description of the Related Art
When the number of discs which can be stored in the stocker is greatly increased, for example, up to 100 discs, it becomes impossible for the user to confirm the position in which the discs are stored and from which a disc can be removed merely by looking. Accordingly, it is necessary to perform a mapping process by which data relating to discs already stored in the disc storage positions in the stocker are recorded in a memory in advance.
Such mapping process is performed using a means which determines the presence of the discs in such positions, which means may be a device using an optical sensor in the each disc storage position, or a device using an optical isolator or a mechanical switch.
However, when optical sensors are attached to all of the disc storage positions, the size of the unit cannot be minimized because the intervals between the shelves of the stocker must be set wide enough to allow for such sensors. In order to minimize the size of the unit, the number of the stored discs would have to be decreased.
If the optical sensors are attached to each of the disc storage positions, the number of the parts is increased in relation to the number of the stored discs, the manufacturing process is difficult, and the cost is increased.
With auto disc changers currently in use, a disc is placed in the disc tray, the disc tray is closed, and the disc is played back or is stored in a specific position in a stocker. The stocker has disc storage positions (shelves) which can store a number of the discs.
With such auto disc changer, when a disc accidentally slips while inside the unit, the disc falls into the unit and the changer may be broken.
In order to avoid this, a stopper may be attached to the rear end of the disc tray which stopper is raised when the disc tray is opened. For example, such stopper may be attached to the inner side portal of the disc tray and when a disc is stored in the unit, the stopper is raised. As the disc tray is being closed, the stopper is lowered to a rest position. The stopper is lowered because it may be necessary to transfer the disc between the carriage and the disc tray when the disc tray is completely closed.
However, with the auto disc changer using the stopper described above, when the disc is roughly placed on the disc tray, the disc may accidentally moves over the top of the stopper and fall into the bottom of the unit. In such situation, the disc is damaged and the auto disc changer may be broken. When the unit is jolted or the unit is tilted for some reason while the disc tray is closing, the disc may be accidentally knocked into the bottom of the unit because the stopper is lowered while the disc tray is closing.
Additionally, a pair of regulators is attached to the right and left sides of the inner side portal of the disc tray, in order to hold a disc in position. The disc regulators are rotatably attached and are biased toward the inside.
Such disc regulators come in contact with the edge of the disc in order to hold the disc while the disc tray is being opened or closed. The disc regulators are rotated outward only when the disc is transferred to and from the disc tray.
However, with the conventional disc tray, when two discs are accidentally placed on the disc tray, the discs will not be correctly loaded and removed.
The carriage can store only one disc, and accordingly, when two disc are placed in the disc tray and simultaneously moved to the carriage, the discs will collide with the portal of the carriage and may be damaged, and the auto disc changer may also be broken.
For example, an auto disc changer 910 currently in use which can store a number of discs 12 and can play back one of the discs 12 at a time, is shown in FIG. 1. Such an auto disc changer 910 has a disc stocker 913 in which a number of discs 12 can be stored at disc storage positions 913A, a carriage 914 which transfers a specified disc 12, a playback block (not shown) for playing back the specified disc 12, and a control block, in a cabinet 911. A transparent window 915 through which the user can see the stored discs 12 is formed into the front panel 911A of the cabinet 911. A tray 916 which loads and removes the discs 12 is positioned below the window 915. A display 917, which indicates the number representing the disc storage positions 913A in which the discs 12 are stored, and operation keys 918 are positioned at the right side of the transparent window 915.
Generally, with the conventional auto disc changer 910, lines 919 indicating the positions of the discs 12 are printed beside the transparent window 915. A longer line is often used to indicate every set of ten discs 12. For example, if the user wishes to confirm that a disc 12 is stored in the 65th level from the bottom, it is easy to locate the 60th level using the longer lines 919 and then count up 5 lines. It is unnecessary to count 65 lines 919 from the bottom. Thus, the user can more easily confirm the position.
However, when such position lines 919 are directly printed on the transparent window 915 with white or black ink, or when a seal on which such lines 919 are printed is laminated onto the transparent window 915, the problems described below arise. In the case of lines 919 that are directly printed onto the window 915, there is generally a wide gap between such window 915 and the discs 12. Accordingly, when the user looks at both the lines 919 and the discs 12 from an angle, the lines 919 may deviate from the corresponding positions of the discs 12. When the seal is laminated onto the window 915, the seal may obstruct the view of the inside, and the user may not be able to confirm whether or not a disc 12 is stored in a specific disc storage position. In order to avoid this, a seal on which pointers 920 are printed may be used on the window 915. However, because the pointers 920 are also much separated by a distance from the discs 12, it again may be difficult to determine which pointer 920 corresponds to which discs 12.